Cutting by means of a high velocity fluid jet is well known in the art. Typically, a fluid, such as water, is forced through a jewel orifice to generate a jet having a pressure from 35,000 to 55,000 psi and a velocity of up to three times the speed of sound. Such a jet may be utilized to cut through a variety of nonmetallic materials such as rubber, plastic, wood, or cloth. The cutting power of the fluid jet may be enhanced by the addition of abrasive particles into the high pressure stream to produce an abrasive waterjet. Abrasive waterjets are effective at cutting a wide variety of metals, such as steel, aluminum and titanium, hard non-metallics, such as rock and concrete, and exceptionally hard materials, such as armor plate, certain ceramics, and tool steel. Typically, abrasive materials used in an abrasive waterjet include garnet, silica, and aluminum oxide.
Abrasive waterjets are also effective at cutting graphite-epoxy composite materials, such as composite panels and I-beam stringers for airplane components. Currently, stringers are cut with an extrusion mill having high speed routers to cut the desired profile of the stringers. Although extrusion mills are effective at cutting I-beam stringers, the resulting cut quality is sometimes poor and each stringer must be reworked to smooth the edges. Because of the high cut quality associated with abrasive waterjets, there is no need to rework the workpiece and, therefore, abrasive waterjets have proven to be a very effective cutting tool for composites, such as panels and I-beam stringers.
In the past, a significant limitation of abrasive waterjets was the size of the catcher to catch or stop the waterjet stream after it has cut through the workpiece. Because of the high fluid pressure associated with waterjets, the waterjet cutting stream is a danger to persons or equipment that may accidentally be impinged by the waterjet. Accordingly, waterjet cutting systems have included an energy dissipating receptacle for receiving the high velocity jet of fluid.
Energy dissipating receptacles, or catchers, currently known in the art suffer from three basic problems. First, conventional catchers, particularly those used with abrasive waterjets, have experienced short useful lives because of the cutting force of the jet and have required relatively expensive wear components. Thus, catchers currently available are usually expensive and require frequent replacements.
Second, the catcher housing has typically been expensive because of the quality and quantity of material from which it is fabricated. Thick metallic walls are required to ensure against penetration by the fluid jet, particularly where abrasive waterjets are utilized. Thirdly, the catcher is typically too large to fit within workpieces having relatively small spacing in which the catcher may be received, such as the vertical spacing between the upper and lower flanges of some I-beam stringers. For example, conventional catchers, such as those disclosed in U.S. Pat. No. 4,651,476 issued to Marx et al., range in length from 4 inches up to 36 inches in the direction of the jet travel. Thus, waterjets cannot be used to cut a workpiece having an available space in which the catcher may be received that is smaller than 4 inches because currently available catchers are too large. In summary, catchers currently available in the art not only have short useful lives, but also are relatively large and expensive.
Thus, there exists a need for a catcher that is both inexpensive and durable to deflect and dissipate the energy from an abrasive waterjet stream, while being sized to fit within a relatively small cutting area. The present invention addresses these issues and other issues to overcome the limitations currently encountered by providing a compact catcher that includes an angled channel to dissipate the energy associated with a high pressure waterjet within a predetermined area.